1. Field of the Invention
The present invention relates to a front loader.
2. Description of Related Art
A front loader disclosed in Related Art 1 is a conventional front loader that prevents soil from spilling out of a bucket during lifting of a boom. The front loader has a boom support fixed to a front portion of a tractor, a boom swingable upward and downward and supported by the boom support in a rear end portion thereof so as to be rotatable around a left-right axis, a bucket bracket pivoted in a front end portion of the boom through a bucket pivot support axis, and a bucket fixed to the bucket bracket so as to be rotatable around the bucket pivot support axis.
The boom is lifted and lowered in association with expansion and contraction of a boom cylinder provided across a middle portion of the boom and the boom support. The bucket performs scooping and dumping in association with expansion and contraction of a bucket cylinder. A bottom end portion of the bucket cylinder is pivoted and connected to the middle portion of the boom. A front end portion of a piston rod of the bucket cylinder is pivoted and connected to first end portions of a pair of bucket links. A second end portion of the first bucket link is pivoted and connected to an upper portion of the bucket pivot support axis of the bucket bracket. A second end portion of the second bucket link is pivoted and connected to a pivot support bracket fixed to the lower surface of the boom and projecting downward therefrom.
The front loader performs dumping of the bucket by projecting the piston rod of the bucket cylinder and performs scooping of the bucket by retracting the piston rod of the bucket cylinder. Furthermore, the front loader has a control valve and a spill guard link mechanism, the control valve allowing the bucket to perform dumping during lifting of the boom, the spill guard link mechanism maintaining the posture of the bucket by controlling the control valve such that the bucket performs dumping in conjunction with lifting of the boom.
Specifically, in the front loader, the boom is lifted in a lifted state where the bucket filled with soil is lifted, and then the spill guard link mechanism controls the control valve from a neutral position to a control position to allow the bucket to perform dumping and maintain the lifted state. Thus, the soil in the bucket can be prevented from spilling.
The spill guard link mechanism has a detection link detecting the dumping of the bucket so as to provide feedback to the control valve of the dumping of the bucket during lifting of the boom having the bucket such that the control valve is controlled in a direction returning to the neutral position. The detection link is disposed at the front end portion of the boom. A first end portion of the detection link is pivoted and connected to a connecting portion provided in the second end portion of the second bucket link to detect the dumping of the bucket based on the movement of the second bucket link.
A second end portion of the detection link is pivoted and connected to a front end portion of a rotation arm provided in the front portion of the boom and rotatable around the left-right axis. The front end portion of the rotation arm is interlocked and connected with a spool of the control valve through a link mechanism. The control valve is provided on the boom support.
[Related Art 1] Japanese Patent Laid-Open Publication No. 2009-52287
In the conventional front loader, the first end portion of the detection link of the spill guard link mechanism is pivoted and connected to the connecting portion in the second end portion of the second bucket link, and the second end portion of the second bucket link is pivoted and connected to the pivot support bracket fixed to the lower surface of the boom and projecting downward therefrom. Thus, there is a circumstance where the first end portion of the detection link may come into contact with the ground. An advantage of the present invention is to provide a front loader that overcomes such a circumstance.